The invention relates to a vehicle having a power electronics unit for the purpose of converting energy between a direct current (DC) circuit and a polyphase machine, wherein the power electronics unit has a power module, a driver circuit board, and a control circuit board. The power electronics unit has two DC current rails, wherein the DC circuit can be connected to the same. The power electronics unit has phase current rails, wherein the polyphase machine can be connected to the same, wherein the number of the phase current rails corresponds to the number of the phases of the polyphase machine.
Power electronics components which are used in modern motor vehicles such as hybrid or electric vehicles are subjected to more critical demands compared to stationary applications such as those in industrial and plant settings. This is true, by way of example, of the geometric construction and the constructed space thereof, as well as temperature resistance or the design for short-term operation.
In vehicles with electric drive trains, electric inverters and/or rectifiers are particularly needed as power electronics components, which convert energy between a DC voltage on-board power supply in the high-voltage range, and a polyphase electric machine. In an electrical inverter, electronic semiconductor high-power switches, which are typically IGBTs (insulated-gate bipolar transistors) are used, grouped into a power module similar to an assembled circuit board. In addition, an inverter commonly has a separate driver circuit board via which the voltage control of the gates is carried out. In addition, an inverter has a control circuit board which has a central processor unit (CPU). The operating voltage of the control circuit board is typically in the low-voltage range, while the driver circuit board and the power module are designed for high-voltage.
In the prior art, the power module is connected to current rails for the flow of the alternating current. The current rails are typically equipped with current sensors. An analog measurement signal is commonly transmitted from the current sensors to the CPU of the control circuit board. As is found in the scientific publication DOI 10.1109/ISPSD.2008.4538886, the measurement signal is alternatively processed at the site of the measurement in a more cost-intensive design.
In US 2004/0066643, an arrangement for current rails and metallic shielding plates is used to minimize the interactions between the electronics and the electromagnetic interference fields caused by the switches of the IGBTs.
The problem addressed by the invention is that of describing a vehicle with an improved power electronics unit.
This problem is addressed by a vehicle with a power electronics unit for the purpose of converting energy between a DC circuit and a polyphase machine. The power electronics unit has a power module, a driver circuit board, and a control circuit board. The power electronics unit has two DC power rails, wherein the DC circuit can be connected to the same. The power electronics unit has phase current rails, wherein the polyphase machine can be connected to the same. The number of the phase current rails corresponds to the number of the phases of the polyphase machine. The power module, the driver board, and the control board are arranged together in a stacked construction. The phase current rail can be electrically connected to the power module. The control circuit board has a passage for each of the phase current rails, wherein one phase current rail can be fed through each passage.
According to the invention, the arrangement of the power module, the driver circuit board, and the control circuit board corresponds to a stacked or sandwiched construction, wherein the phase current rails are connected to the power module. In addition, the control circuit board has a passage for each of the phase current rails, through which the phase current rail is fed. In this way, the effect of the phase current rail being arranged at the least possible distance in space from the control circuit board is achieved.
According to one preferred embodiment of the invention, the control circuit board has a current sensor at each passage, and each current sensor measures the current in the respective phase current rail. This provides the particular advantage that the current sensors, which determine the phase current of the electrical machine in the respective phase current rail, can be integrated on the control circuit board due to the arrangement of the phase current rails.
According to a further variant of the invention, the control circuit board has a central processor unit and an analog data link to each of the current sensors. Each current sensor transmits a current measurement signal via the data link which is functionally assigned to the sensor.
The data links are preferably designed as cable connections via which an analog measurement signal is transmitted from each respective current sensor to the central processor unit. In this case, it is particularly advantageous that a length of the cable connection between the current sensor and the central processor unit results from the short distance in space. For this reason, the sensitivity of the current measurement signal to electromagnetic interference is low.
One particular advantage results from the vehicle being designed as an electric or hybrid vehicle. Electric and hybrid vehicles have an electrified drive train in the high-voltage range up to 380 Volts. The drive train must be controlled as precisely as possible due to the great number of operating states and influencing parameters. A nearly interference-free measurement of the phase currents of the electrical machine makes a contribution toward this goal.
The invention is based on the following considerations: in electric and hybrid vehicles, current sensors are used in the power electronics to measure the phase currents of the electrical machine. These current sensors have paramount significance in the regulation of the electrical machine. For this reason, interferences or phase shifts of the current measurement signals coming from the current sensor must be avoided no matter what. By means of a skillful topological arrangement of the circuit boards of the power electronics, it is possible to decisively improve the signal quality. This can be achieved by placing the phase current sensors on the controller board to minimize the conductor path lengths between the current sensor and the analog-to-digital converter of the CPU. For this purpose, the power rails for the individual phases are routed through the controller board. As a result, a potential for saving on material costs and weight arises.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.